The purpose of this research is (1)\to understand the intermediary metabolism of tyrosine/dopa metabolites (melanogens) involved in melanogenesis of metastatic melanoma and (2)\to use the tumor-related urinary melanogens for determining the tissue site of the metastasis. To do this, we are comparing the melanogens isolated from the tissue-specific metastases as (a) tumor extracts, (b) cell culture medium of the tumors and (c) urine of the tumor-bearing animals (hamsters). We have developed tissue-specific tumors of the liver, kidney, lung, testes and gut through repeated i.v., i.p. and s.c. propagation. We have found it necessary to use 20% serum (calf, fetal calf, normal hamster, tumored hamster and human) to sustain the cells but find little growth of cells in culture. Serum-free medium (Nu-serum, a serum substitute) is necessary to obtain melanogens from the cultured tumor cells. A high cell density is necessary to obtain sufficient melanogen concentration to be detected by the cat-ion exchange column chromatography assay. Concentrating the melanogens by ethyl acetate extraction makes it possible to obtain sufficient melanogen for chromatographic detection. The melanogens are labile and should be extracted from the media at 1 to 3 hours after inoculation with tumor cells. The amounts of compounds released to the media is less than observed in urine of the tumor-bearing animal indicating that there is secondary metabolism of the melanogens after they leave the in situ tumor. The anticancer drug decarbazide (DTIC), when administered to the tumored animal, reduced the number of melanogens. This drug only slowed the tumor growth rate as the animal became sick from the treatment. The melanogen biochemistry of both the normal and tumored animal appear to be affected. We have also been able to detect a hamster metastatic eye melanoma by chromatographic urine analysis. The metastatic eye melanoma was propagated by i.v. injection of cells from a 2-year-old metastatic eye melanoma we have isolated.